Classifications

• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B16/00—Use of organic materials as fillers, e.g. pigments, for mortars, concrete or artificial stone; Treatment of organic materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone
  • C04B16/04—Macromolecular compounds
  • C04B16/06—Macromolecular compounds fibrous
  • C04B16/0616—Macromolecular compounds fibrous from polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • C04B16/0641—Polyvinylalcohols; Polyvinylacetates
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
  • C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
  • Y02W30/00—Technologies for solid waste management
  • Y02W30/50—Reuse, recycling or recovery technologies
  • Y02W30/91—Use of waste materials as fillers for mortars or concrete

Definitions

• the invention relates to a building material consisting of binders, preferably hydraulic binders such as cement, gypsum, alkali aluminates, alkali silicates, fillers and additives as well as fibrous or fibrous mixture components.
• binders preferably hydraulic binders such as cement, gypsum, alkali aluminates, alkali silicates, fillers and additives as well as fibrous or fibrous mixture components.
• the mixtures are particularly suitable for the production of thin-shelled building materials, for example flat panels, corrugated panels, moldings, pipes and a wide variety of roof and facade materials.
• fiber-reinforced building materials are characterized by the fact that they have relatively high strengths combined with high impact strengths with a small thickness.
• asbestos was used almost without exception as a fibrous mixture component in such mixtures. After it began to emerge from around 1978 that asbestos could no longer be used industrially to this extent for a variety of reasons - economically and also because of possible health risks - an intensive search for new fiber-containing building material mixtures began, which are the tried and tested asbestos cement products of the building materials industry could replace.
• polyvinyl alcohol fibers must have a modulus of elasticity of at least 130 g / dtex and an elongation at break of maximum 4-8% so that they are able to reinforce cement.
• Such high modulus fibers can only be produced using a technically complex spinning process, which explains the high costs for these special fibers.
• EP-A-0 220 649 proposes to use very fine PVA fibers, which allow the production of boards using a low fiber content on a Hatschek system. This enables savings in the process fibers (pulp pulp, synthetic pulp) to be achieved, since the very fine PVA fibers act simultaneously as reinforcing fibers and as process fibers.
• the very fine PVA fibers also have various disadvantages, so that they cannot generally be used in the regular manufacture of fiber cement products.
• the preparation of the fiber slurry is also more complicated, and a special inorganic dispersing aid is required in order to distribute the fine fibers evenly.
• the recommended dispersion aid namely sepiolite, shows also a potential health hazard comparable to that of asbestos.
• the very fine fibers have to be cut much shorter, to 2-3 mm, than conventional fibers, whose cutting lengths are 4-6 mm, otherwise problems with spinning occur.
• EP-A-0 155 520 gives further possibilities for reducing the costs for the reinforcing fibers used in fiber cement products.
• the inventors have found that there is a possibility to replace a substantial part of the expensive high modulus PVA fibers with cheaper high modulus PAN fibers without losing the excellent production properties.
• the PAN fibers While the binding of the PVA fibers to the cement is mainly based on physical forces, the PAN fibers develop chemical bonds with the cement matrix due to the hydrolysis of the nitrile groups on the outermost surface of the PAN fibers. During the As the product ages, the resulting carboxyl groups tend to increase, and at the same time the fibers bind to the matrix. All of these reactions increase the embrittlement of the products.
• the present invention now makes it possible to produce high quality cement products with excellent aging behavior by using only special PVA fibers.
• the mixtures for producing the fiber-reinforced, thin-shelled building materials according to the invention preferably consist of an inorganic binder such as cement, which harden by hydration.
• an inorganic binder such as cement, which harden by hydration.
• Portland cement, melt cement, iron Portland cement, trass cement, blast furnace cement or gypsum are particularly suitable.
• Fillers and additives such as limestone powder, amorphous silicas, fly ash, quartz, kaolins, talc, rock powder etc. are also preferably added to the hydraulic binder.
• the polyvinyl alcohol fibers according to the invention are added to the cementitious material as short cuts in 1-10% by weight.
• the fibers have an elongation of 8.5 - 15% and a strength of 40 - 90 cN / dtex.
• Such PVA fibers are made from polymers of the general formula (CH2-CH (OH) -) n obtained with molecular weights of, for example, 20,000-100,000 and a density of 1.23-1.32.
• the PVA raw material is usually produced by saponification of polyvinyl acetate and the fibers are produced using a conventional wet spinning process (see for example: Handbook of Fiber Science and Technology, Volume IV, Fiber Chemistry, Marcel Dekker Inc., New York and Basel, from page 547).
• Such polyvinyl alcohol fibers can still adhere to up to 20% by weight of sodium sulfate due to the production.
• the fibers are preferably added in a cutting length of 2-12 mm. Uniformly long individual fibers as well as fibers of different lengths and also ground fibers can be used.
• the titer of the individual fibers can fluctuate in a wide range, but titres in the range of 0.5-5 dtex have proven themselves.
• the fibers can be in the cement matrix be evenly distributed, or, in the case of special components, are present in increased concentrations at locations which are exposed to directional mechanical stresses.
• the fibers can also be used in the form of non-woven fabrics, tapes, nets, knitted fabrics, fabrics etc. Depending on the production conditions of the fibers, their cross-sections can be varied in a variety of ways, so that from round fibers to multilobal fibers to hollow fibers can result. It is also possible to add pigments, fillers and other additives to the spinning solution before fiber production.
• polyvinyl alcohol is a substrate with a high chemical reactivity
• the fibers can also be modified by means of finishing agents or adhesion promoters without any actual reactions.
• polyvinyl alcohol fibers according to the invention used as reinforcing fibers can be admixed to the cementitious substrate alone or in admixtures with other reinforcing fibers.
• High-modulus polyvinyl alcohol fibers and natural fibers such as ramie fibers or cellulose fibers are also suitable as additional reinforcing fibers.
• Aqueous fiber cement mixtures which are dewatered with the help of sieves, are also process-related additional fibrous materials are added, which increase the cement retention capacity.
• pulps are mainly wood pulp fibers, waste paper, cellulose fibers and fibrids made of plastics such as polypropylene, polyethylene etc.
• the PVA fibers used according to the present invention and the high-modulus PVA fibers protected according to DE-PS 2 850 337 had the following textile mechanical properties: Fiber properties High modulus PVA fibers according to DE-PS 28 50 337 PVA fibers according to the present invention Cutting length 6 mm 6 mm Titre dtex 2.0 1.6 Elongation at break% 7.4 9.6 Tear resistance cN / dtex 11.7 6.0 A module CN / dtex 279.0 120.0
• This entire aqueous fiber-cement slurry was diluted to a solids content of 80 g / l using a continuous mixer and fed into the fabric box of a Hatschek machine.
• a dilute aqueous solution of a flocculant based on Polyacrylamide added to further improve the cement retention during the subsequent drainage stage.
• Example 1 shows the prior art, the addition of 2% high-modulus PVA fibers resulting in products with high specific strengths combined with high breaking work.
• Comparative example 5 shows that, according to EP-A 0 155 520, even cheaper fiber blends can lead to similar short-term properties, but after a year of outdoor exposure there is a clear embrittlement.
• Examples 3 and 4 according to the invention show that even with cheap PVA fibers alone, which have lower strengths and higher elongations at break, or in blends (example 2), fracture mechanical values can be achieved, which are otherwise only obtained with the expensive high-modulus PVA fibers without exhibiting the disadvantageous embrittlement according to EP-A 0 155 520.
• the present invention accordingly relates to a thin-shelled fiber-reinforced building material which is characterized in that it contains 1-10% by weight of short-cut polyvinyl alcohol fibers which have an elongation of 8.5-15% and a strength of 40-90 cN / dtex , or a method for producing such a fiber-reinforced hydraulically set building material or the use of polyvinyl alcohol fibers with the characteristics mentioned for producing such a fiber-reinforced material.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Ceramic Engineering (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Materials Engineering (AREA)
• Structural Engineering (AREA)
• Organic Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Curing Cements, Concrete, And Artificial Stone (AREA)
• Laminated Bodies (AREA)
• Manufacture Of Alloys Or Alloy Compounds (AREA)
• Moulding By Coating Moulds (AREA)
• Reinforced Plastic Materials (AREA)
• Artificial Filaments (AREA)
• Paper (AREA)
• Compositions Of Macromolecular Compounds (AREA)

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Applications Claiming Priority (2)

Publications (2)

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Cited By (6)

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Citations (2)

• 1989
  • 1989-10-10 ES ES89118778T patent/ES2034551T3/es not_active Expired - Lifetime
  • 1989-10-10 AT AT89118778T patent/ATE78457T1/de not_active IP Right Cessation
  • 1989-10-10 DE DE8989118778T patent/DE58901882D1/de not_active Expired - Fee Related
  • 1989-10-10 EP EP19890118778 patent/EP0363891B1/fr not_active Expired - Lifetime
  • 1989-10-11 YU YU197189A patent/YU46493B/sh unknown
  • 1989-10-12 DK DK505889A patent/DK169430B1/da not_active IP Right Cessation
  • 1989-10-12 CS CS579389A patent/CS275354B2/cs not_active IP Right Cessation
  • 1989-10-12 DD DD89333537A patent/DD298959A5/de not_active IP Right Cessation
  • 1989-10-13 HU HU895310A patent/HU211066B/hu not_active IP Right Cessation

Patent Citations (2)

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